DESCRIPTION (investigator's abstract): The application seeks support for a study of daily stress and well-being during adulthood. The specific aims are to: a) describe how multiple aspects of daily stressors (e.g., frequency, content, severity) predict daily well-being during adulthood; b) examine how sociodemographic factors (e.g., age, gender, socioeconomic status) and personality characteristics influence exposure to daily stressors and moderate physical, emotional, and social reactivity to daily stressors; and c) explore the role of genetics in exposure and reactivity to daily stressors throughout adulthood. These aims would be achieved by conducting analyses of the National Study of Daily Experiences (NSDE), a telephone diary study of a U.S. national sample of 1483 adults ranging in age from 25 to 74 years. Although a small number of daily diary studies have advanced the understanding of the role of adult development and personality in daily stress processes, there are important limitations in these studies that could be addressed in the present study. First, previous daily diary studies have relied on small and often unrepresentative samples with a restricted age range that limit the generalizability of findings. The present study overcomes this limitation by analyzing data from a fairly large (N - 1483) and nationally representative sample of adults in the age range 25 to 74 years. These respondents are a representative sub-sample of a general population survey of adult development. Second, previous studies of group and individual differences in exposure and reactivity to daily stressors have typically examined only one source of variability. The present study would correct this problem by utilizing the data collected in the larger survey on a wide array of sociodemographic and personality variables to examine the determinants of exposure and reactivity to daily stressors. Third, previous studies have failed to investigate the role of genetics in both exposure and reactivity to daily stressors. The NSDE uses a sub-sample of 242 identical and same-sex fraternal twin pairs to explore how genes and environment interact to account for individual differences in adaptation to day-to-day stressful experiences.